Playframework 在morphia模型中持久化拥有对象id

我有两节课

Movie
  Collection<Session> sessions;
Session
  Movie movie;

然后是会话上的方法：

Object movieId;
setMovie(Movie movie) {
    this.movieId  = movie.getId();
}

我可以保存电影和会话对象，但是当我尝试使用Movie.findById检索电影时，会在下面看到堆栈跟踪

但是，如果我没有在会话上设置movieId字段，那么我可以成功地检索所拥有的电影

你知道我做错了什么吗

java.lang.ClassCastException: org.bson.types.ObjectId cannot be cast to com.mongodb.DBObject at com.google.code.morphia.mapping.EmbeddedMapper.fromDBObject(EmbeddedMapper.java:136) at com.google.code.morphia.mapping.Mapper.readMappedField(Mapper.java:507) at com.google.code.morphia.mapping.Mapper.fromDb(Mapper.java:484) at com.google.code.morphia.mapping.ReferenceMapper.resolveObject(ReferenceMapper.java:277) at com.google.code.morphia.mapping.ReferenceMapper.readCollection(ReferenceMapper.java:225) at com.google.code.morphia.mapping.ReferenceMapper.fromDBObject(ReferenceMapper.java:143) at com.google.code.morphia.mapping.Mapper.readMappedField(Mapper.java:505) at com.google.code.morphia.mapping.Mapper.fromDb(Mapper.java:484) at com.google.code.morphia.mapping.Mapper.fromDBObject(Mapper.java:267) at com.google.code.morphia.query.MorphiaIterator.convertItem(MorphiaIterator.java:66) at com.google.code.morphia.query.MorphiaIterator.processItem(MorphiaIterator.java:53) at com.google.code.morphia.query.MorphiaIterator.next(MorphiaIterator.java:48) at com.google.code.morphia.query.QueryImpl.get(QueryImpl.java:365) at play.modules.morphia.Model$MorphiaQuery._get(Model.java:1045) at models.morphia.Movie.findById(Movie.java) at models.MovieTest.testSave(MovieTest.java:37) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20) at play.test.PlayJUnitRunner$StartPlay$1$1$1.execute(PlayJUnitRunner.java:73) at play.Invoker$Invocation.run(Invoker.java:265) at play.Invoker.invokeInThread(Invoker.java:67) at play.test.PlayJUnitRunner$StartPlay$1$1.evaluate(PlayJUnitRunner.java:68) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184) at org.junit.runners.ParentRunner.run(ParentRunner.java:236) at play.test.PlayJUnitRunner.run(PlayJUnitRunner.java:48) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

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您希望在会话中保留电影和电影ID，这看起来很奇怪

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根据您的使用情况，您可能会使movieId暂时化，或者将其声明为org.bson.types.ObjectId。

很好，谢谢-将id保存为ObjectId而不是Object就是诀窍！尽管我在调用movie.getIdd时必须从Object进行转换，但我想这与它的存储方式有关？为了清楚起见，我不保存电影，只保存id。 java.lang.ClassCastException: org.bson.types.ObjectId cannot be cast to com.mongodb.DBObject at com.google.code.morphia.mapping.EmbeddedMapper.fromDBObject(EmbeddedMapper.java:136) at com.google.code.morphia.mapping.Mapper.readMappedField(Mapper.java:507) at com.google.code.morphia.mapping.Mapper.fromDb(Mapper.java:484) at com.google.code.morphia.mapping.ReferenceMapper.resolveObject(ReferenceMapper.java:277) at com.google.code.morphia.mapping.ReferenceMapper.readCollection(ReferenceMapper.java:225) at com.google.code.morphia.mapping.ReferenceMapper.fromDBObject(ReferenceMapper.java:143) at com.google.code.morphia.mapping.Mapper.readMappedField(Mapper.java:505) at com.google.code.morphia.mapping.Mapper.fromDb(Mapper.java:484) at com.google.code.morphia.mapping.Mapper.fromDBObject(Mapper.java:267) at com.google.code.morphia.query.MorphiaIterator.convertItem(MorphiaIterator.java:66) at com.google.code.morphia.query.MorphiaIterator.processItem(MorphiaIterator.java:53) at com.google.code.morphia.query.MorphiaIterator.next(MorphiaIterator.java:48) at com.google.code.morphia.query.QueryImpl.get(QueryImpl.java:365) at play.modules.morphia.Model$MorphiaQuery._get(Model.java:1045) at models.morphia.Movie.findById(Movie.java) at models.MovieTest.testSave(MovieTest.java:37) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20) at play.test.PlayJUnitRunner$StartPlay$1$1$1.execute(PlayJUnitRunner.java:73) at play.Invoker$Invocation.run(Invoker.java:265) at play.Invoker.invokeInThread(Invoker.java:67) at play.test.PlayJUnitRunner$StartPlay$1$1.evaluate(PlayJUnitRunner.java:68) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184) at org.junit.runners.ParentRunner.run(ParentRunner.java:236) at play.test.PlayJUnitRunner.run(PlayJUnitRunner.java:48) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)